Nowadays, most such bags are fitted with a slider designed to facilitate opening and closing the bags, respectively by separating and engaging closure strips.
In conventional manner, such sliders essentially define two channels receiving respective ones of the two closure strips, the channels being separated by a middle partition that is positioned between the two strips, or being associated with equivalent means adapted to act on the strips. The two channels converge towards each other at one end of the slider and diverge from each other towards the opposite end thereof.
Thus, depending on the direction in which the slider is moved, it tends either to move the strips towards each other and bring them into engagement so as to close the bag, or else to move them apart so as to open the bag.
Furthermore, at present, there exists a strong demand for a system that can be used to show whether or not such a bag has been opened for the first time.
Such first-opening markers that are available on the market are generally in the form of a web placed inside the closure strips and interconnecting the two walls of the bag, the web being designed to be ruptured on first opening, e.g. as described in document FR-A-2 546 481.
Proposals have also been made for packaging bags with closure strips, a slider associated therewith, and a marker strip placed on the path of the slider and designed to be ruptured by the slider on first opening.
In document FR-A-2 817 843, the Applicant has proposed a variant of such bags in which the marker strip is of two colors, presenting different colors respectively on its inside and outside faces.